package com.ebao.util.encrypt;

import java.security.MessageDigest;

/**
 * @author snow
 * @date 2012-5-24
 */
public class MD5 {

	private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
			"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

	private static String byteToHexString(byte b) {
		int n = b;
		if (n < 0) n = 256 + n;
		int d1 = n / 16;
		int d2 = n % 16;
		return hexDigits[d1] + hexDigits[d2];
	}

	/**
	 * 转换字节数组为16进制字串
	 * 
	 * @param b  字节数组
	 *            
	 * @return 16进制字串
	 */

	public static String byteArrayToHexString(byte[] b) {
		StringBuffer resultSb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			resultSb.append(byteToHexString(b[i]));
		}
		return resultSb.toString();
	}

	public static String MD5Encode(String origin) {
		String resultString = null;
		try {
			resultString = new String(origin);
			MessageDigest md = MessageDigest.getInstance("MD5");
			resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
		} catch (Exception e) {
			System.err.println("MD5加密出现异常: " + e.getMessage());
		}
		return resultString;
	}

	/**
	 * MD5加密
	 * 
	 * @author alfred
	 */
	public String getMD5(String str) {
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(str.getBytes());
			byte b[] = md.digest();

			int i;
			StringBuffer buf = new StringBuffer("");
			for (int offset = 0; offset < b.length; offset++) {
				i = b[offset];
				if (i < 0)  i += 256;
				if (i < 16) buf.append("0");
				buf.append(Integer.toHexString(i));
			}

			return buf.toString();

		} catch (Exception e) {
			e.printStackTrace();
			return str;
		}
	}

}